Windmills have been used for many generations for the purpose of pumping water from the ground and for generating electricity. A basic advantage of the windmill is that it uses the power of atmospheric wind to rotate a wheel having radially extending blades. This rotary movement may be converted into various useful purposes, including the generation of electricity. For example, wind turbines include radially extending blades in the form of propellers mounted on towers that have been placed in areas about the U.S.A. where steady winds are prevalent and the wind turbines are used to generate electricity.
The blades of the conventional wind turbines usually are very large and made of expensive rigid material and are constructed to have the blades extend radially from a central hub, with no extra support beyond the axis of rotation of the central hub. These conventional wind turbine blades usually rotate at high rates of revolution and must withstand the centrifugal forces generated by the fast revolution of the blades, the cantilever bending forces applied to the blades by the wind, and the twisting forces applied to the pitched surfaces of the blades. Since the outer portions of the turbine blades may move at a very high velocity when engaged by strong winds, the longer blades require the blades to be strong, and the stronger they are the more expensive they become. Thus, there is a practical limit as to the length and width of the blades of wind turbines.
Prior art wind turbines usually are mounted on upright towers and the towers are supported at their bases by mounting the towers in the earth or on some other stable platform. When the wind turbine is in operation with an oncoming brisk wind engaging the angled blades of the turbine wheel, a significant horizontal force is applied to the turbine blades, tending to move the turbine blades in the direction of the wind horizontally toward the tower. This reduces the distance between the turbine blades and the tower.
Some of the prior art electrical wind turbines are constructed with a circular rim that is concentric with and extends about and rotates with the turbine wheel at a position away from the axis of rotation of the blades, and the turbine blades are supported by the circular rim. Rubber tires that are connected to electrical generators may be placed with their perimeters in positions to engage the circular rim of the wind turbine so that the circular rim of the wind turbine drives and rotates the rubber tires. The driven rubber tires rotate the rotors of the electrical generators. Thus, the rotation of the wind turbine is used to generate electricity. However, the circular rim of the turbine blades also moves horizontally with the turbine blades, which is axially of the turbine wheel, toward the upright tower. This tends to separate the circular rim of the turbine wheel from the rubber tires of the generator.
The prior art includes wind turbines with circular rims that drive electrical generators, such as U.S. Pat. Nos. 8,373,298 and 8,258,645. There is still a need for a more reliable and inexpensive structure and method for supporting the electrical generator and the tire that engages the circular rim of the wind turbine in a manner that causes the tire to follow the horizontal movements of the circular rim.